JP2002333682A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which has a print head arranged with a multiplicity of elements capable of recording image information on a recording paper along a main scanning direction and drive means for moving and controlling the print head in a subscanning direction by exerting a control force on a prescribed point to be controlled of the print head and hardly gives rise to belt-like defects in a foamed image even if the scanning speed in the subscanning direction is increased. SOLUTION: The prescribed point to be controlled is positioned near the centroid of the digital print head relating to the main scanning direction by a technique of arranging a weight 28 or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a digital print head in which a large number of pixel forming elements capable of recording pixel information on recording paper are arranged along a main scanning direction. Driving means for reciprocating the digital print head along a sub-scanning direction intersecting the main scanning direction by applying an operating force to a predetermined operated portion of the digital print head in the main scanning direction. The present invention relates to an image forming apparatus having the same.

[0002]

2. Description of the Related Art In the above-described image forming apparatus, a digital print head itself is driven while driving a large number of pixel forming elements arranged on a digital print head along a main scanning direction based on given image information. Is moved along the sub-scanning direction by the driving means, so that two-dimensional pixel information can be recorded on the recording paper.

Further, in order to reduce the size of the image forming apparatus in the height direction (the size in the thickness direction of the recording paper as an object of image formation) as small as possible, the digital print head is used. A second image forming apparatus of a projection exposure type for forming an image on a photosensitive material such as photographic paper using transmitted light from a photographic film, for example, above the image forming apparatus provided above. Is provided so that when the second image forming apparatus is used, the digital print head can be retracted to one end in the sub scanning direction so as not to be interposed in the optical path of the transmitted light. In another example, before receiving the operating force from the driving means, another secondary purpose that a screw shaft or the like as the driving means of the digital print head cannot be interposed in the optical path of the transmitted light. Given the operated position, such as hardly disposed above the pixel-forming elements, therefore, are provided near the end of the digital print heads in the main scanning direction.

However, in the image forming apparatus having the above configuration,
As the scanning speed in the sub-scanning direction is increased in order to increase the efficiency of the image forming process, a band-like defect extending in the main scanning direction tends to occur in the formed image.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-mentioned drawbacks of the prior art image forming apparatus even if the scanning speed in the sub-scanning direction is increased. It is an object of the present invention to provide an image forming apparatus in which a band-like defect extending in the main scanning direction in an image is less likely to occur.

[0006]

In order to achieve the above object, an image forming apparatus according to the present invention has the features described in claims 1 and 2 in the claims.
That is, an image forming apparatus according to claim 1 of the present invention includes a digital print head in which a large number of pixel forming elements capable of recording pixel information on recording paper are arranged along the main scanning direction.
Driving means for reciprocatingly operating the digital print head along a sub-scanning direction intersecting the main scanning direction by applying an operating force to a predetermined operated portion of the digital print head in the main scanning direction. An image forming apparatus, wherein the predetermined operated portion is arranged near a center of gravity of the digital print head in the main scanning direction.

[0007] In order to have such a characteristic configuration,
In the image forming apparatus according to the first aspect of the present invention, when attention is paid to the inertial force acting on the digital print head in the sub-scanning direction based on the speed and acceleration of the operating force applied from the driving means to the predetermined operated portion, the digital printing is performed. On the head, the magnitude of the inertial force acting on the portion extending to the one side from the predetermined operated position with respect to the main scanning direction, and the magnitude of the inertial force acting on the portion extending to the other side from the predetermined operated position. Since the size is substantially equal, the phenomenon in which the inertia force preferentially acts on only one of the predetermined operated portions in the main scanning direction on the digital print head is suppressed. Therefore, even when the scanning speed in the sub-scanning direction is increased, the vibration of the digital print head (vibration along the surface of the recording paper) centered on the vicinity of the predetermined operated portion is suppressed, and the recording head is formed on the recording paper. A band-like defect extending in the main scanning direction hardly occurs in an image.

[0008] As a specific configuration, a weight for displacing the center of gravity of the digital print head near the predetermined operated portion can be provided in the digital print head. With such a configuration, the structure of the driving means and the driving means can be achieved by simply performing a simple process of adding a weight having an appropriate weight to an appropriate position on the digital print head of the conventional image forming apparatus. Basically, the image forming apparatus according to the present invention can be realized without making any special changes to the components provided in the digital print head for inputting the operation force from the digital print head.

According to another aspect of the present invention, there is provided an image forming apparatus according to the present invention.
And 4 are provided. That is,
According to a third aspect of the present invention, there is provided an image forming apparatus, comprising: a digital print head in which a large number of pixel forming elements capable of recording pixel information on recording paper are arranged along the main scanning direction; A driving unit that reciprocates the digital print head in a sub-scanning direction that intersects the main scanning direction by applying an operating force to a predetermined operated portion in the digital forming apparatus. The print head has a print head main body including the plurality of pixel forming elements, and an input unit including the predetermined operated portion while supporting the print head main body on one side in the main scanning direction. A weight for positioning the center of gravity of the digital print head near the predetermined operated position in the main scanning direction; With respect to a predetermined target operation point, and the characteristic configuration that is attached to the position opposite to the print head body of the input unit.

[0010] In order to have such a characteristic configuration,
In the image forming apparatus according to a third aspect of the present invention, the center of gravity of the digital print head is located near the predetermined operated position due to the effect of the weight. Therefore, when focusing on the inertial force in the sub-scanning direction that acts on the digital print head based on the speed and acceleration of the operating force that acts on the predetermined operated portion from the driving unit, the digital scanning head has the following main scanning direction. Since the magnitude of the inertial force acting on the part extending from the predetermined operated part to one side and the magnitude of the inertial force acting on the part extending from the predetermined operated part to the other side are substantially equal, the digital printing is performed. The phenomenon in which the inertial force acts preferentially on only one of the predetermined operated portions in the main scanning direction on the head is suppressed. Therefore, even if the scanning speed in the sub-scanning direction is increased, the vibration of the digital print head (vibration along the surface of the recording paper) centered on the vicinity of the predetermined operated portion is suppressed, and the recording head is formed on the recording paper. A strip-shaped defect extending in the main scanning direction hardly occurs in the image.

More specifically, the driving means has a screw shaft extending along the sub-scanning direction, and a driving motor for driving the screw shaft to rotate. An input nut fixed to the digital print head so as to be screwed into the digital print head, and a guide mechanism that regulates rotation of the digital print head around the screw axis is provided. A rod-shaped guide member extending parallel to the screw shaft and an engaging portion provided between the print head body and the weight so as to engage with the guide member while sliding with respect to the guide member. It can be configured.

With such a configuration, both the screw shaft for transmitting the operation force to the digital print head and the rod-shaped guide member for restricting the rotation of the digital print head around the screw shaft are used for printing. Since it is provided close to a relatively narrow area between the head main body and the weight, even if the scanning speed in the sub-scanning direction is increased, the vibration of the digital print head centering around a predetermined operated position is reduced. The suppressed image forming apparatus can be obtained in a compact form.

[0013] Other features and advantages of the present invention include:
The description will become apparent from the description of the embodiment using the drawings.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As one embodiment of the present invention, a photographic printer provided with an image forming apparatus according to the present invention will be described.
This will be described below with reference to the drawings. (Overall Configuration of Photo Printer) The photo printer 100 shown in FIGS. 1 and 2 has an exposure processing unit Ex for exposing a given image to photographic paper (an example of recording paper), and developing the exposed photographic paper. And a development processing unit De for processing. The exposure processing unit Ex has a photographic paper magazine 1 capable of accumulating a long unexposed photographic paper LP in a roll form, a drawer roller unit 2 for drawing out the photographic paper LP from the photographic paper magazine 1 by an appropriate length, and an exposure processing unit Ex. Cutter 3 for cutting photographic paper LP,
An exposure unit 4 which receives a rectangular sheet of photographic paper SP made by the cutter 3 and performs an exposure operation of an image given to the photographic paper SP supported on the exposure table 4 which is fixed and supported; The photographic paper SP that has been subjected to the exposure operation is
And an intermediate transport mechanism 8 which transfers the emulsion surface of the photographic paper SP to the development processing unit De so that the emulsion surface faces outward.

The exposure table 4 includes an endless belt 5 in the form of a rubber film,
Support roller 6 for supporting endless belt 5 at at least three points
a, 6b, 6c and 2 arranged at substantially the same level as each other.
In order to transport the portion of the endless belt 5 stretched between the two support rollers 6a and 6c from the cutter 3 to the side of the intermediate transport mechanism 8, the support rollers 6 are controlled based on an instruction from a control device (not shown). And a drive motor for rotating at least one of the above. In addition, a large number of through holes are formed on the entire surface of the endless belt 5, and on the back side of the endless belt 5 stretched between the two support rollers 6a, 6c, the endless belt 5 is provided. A suction device 7 for fixing the placed photographic paper SP on the endless belt 5 with a negative pressure through the through hole is provided.

The leading end of the photographic paper SP provided from the cutter 3 is fixed on the endless belt 5 by a suction device 7,
Subsequently, based on the rotation drive of the endless belt 5 and the subsequent stop of the endless belt 5, it is disposed below the exposure unit EU. The intermediate transport mechanism 8 includes a roller pair assembly 9 that receives the photographic paper SP from the endless belt 5 that is driven to rotate again after the exposure operation by the exposure unit EU is completed,
A transport mechanism (not shown) for transferring the roller pair assembly 9 to the development processing unit De while transferring the roller pair assembly 9 to the development processing unit De by about 90 °.

When a photographic printer is used for color photographic processing, for example, the development processing unit De includes a number of processing tanks 11 for holding processing solutions such as a color developing solution, a bleach-fixing solution, and water for washing. In order to successively guide the photographic paper SP received from the transfer roller mechanism 10 to the developing solution in each processing tank 11, a transport rack (not shown) arranged in each processing tank 11 is provided. Further, downstream of the processing tank 11, a drying processing unit D for drying the developed photographic paper SP is provided.
and a discharge port 12 for discharging the completed photographic print after drying to the outside of the photographic printer. The exposure unit EU includes a first exposure unit E having a projection exposure unit.
Ua and a second exposure unit EUb having a digital exposure head.

(First Exposure Unit EUa) The first exposure unit EUa has a film carrier 14 for supporting a photographic film F that has been exposed and developed, and a lamp house 15 disposed above the film carrier 14. White light emitted from a halogen lamp 15a (an example of a light source) provided in the lamp house 15 passes through a color filter (not shown) for correction and a mirror tunnel (not shown), and is supported by the film carrier 14. The photographic film F is irradiated, and the transmitted light formed thereby is condensed
After passing through, the photographic paper SP on the support surface of the exposure table 4 is exposed to form a latent image of the image carried on the photographic film F on the photographic paper SP.

(Second Exposure Unit EUb) As shown in FIG. 3, the second exposure unit EUb is provided on the exposure table 4 so as to be close to the emulsion surface of the photographic paper SP supported on the exposure table 4. It has a frame member 20 disposed above and a digital exposure head 21 (an example of a digital print head) provided with a large number of light emitting elements (an example of a pixel forming element) arranged along the main scanning direction. The digital exposure head 21 has an exposure head body 22 (an example of a head print head body) in which a large number of light emitting elements are incorporated, and a support member 23 extending in the main scanning direction to support the exposure head body 22. . The support member 23 includes a base end 23a (an example of an input unit) that is displaced to one end of the exposure head main body 22 in the main scanning direction, and an arm extending from an upper portion of the base end 23a to one side in the main scanning direction. A portion 23b. The exposure head main body 22 is supported on the lower surface of the arm 23b.

The second exposure unit EUb is provided with a ball screw mechanism 24 (an example of a driving means) for reciprocating the digital exposure head 21 in the sub-scanning direction.
The ball screw mechanism 24 includes a ball screw 25 (an example of a screw shaft) rotatably supported by the frame member 20, and a base end 23 a of the support arm 23 so as to be screwed with the ball screw 25.
A ball nut 23 </ b> N (an example of an input nut and a predetermined operated portion) fixed to the motor and a drive motor 26 that rotationally drives the ball screw 25. Ball screw 25
Extend along the sub-scanning direction. When the ball screw 25 is rotated by the drive motor 26, the ball screw 2
5 operates in the sub-scanning direction.
The information is transmitted to the ball nut 23N as a predetermined operated portion in the main scanning direction. Further, the second exposure unit EUb is provided with a guide mechanism for accurately and linearly guiding the digital exposure head 21 in the sub-scanning direction. The guide mechanism includes a linear guide member 27 supported by the frame member 20 so as to extend in parallel with the ball screw 25, and a support arm that engages with the linear guide member 27 while sliding with respect to the linear guide member 27. Engaging part (not shown) provided at base end 23a of 23
Consists of The linear guide member 27 has a non-circular cross-sectional shape, and as the engaging portion, is rotatable around the base end 23a of the support arm 23 in order to support the linear guide member 27 from a plurality of positions in the outward direction. Can be constituted by a plurality of balls (not shown, an example of an engaging portion) arranged in the first position. The linear guide member 27 is connected to the digital exposure head 21.
Also functions as a guide mechanism for restricting rotation around the ball screw 25.

(Weight of Digital Exposure Head) As shown in FIG. 3, the center of gravity of the digital exposure head 21 in the main scanning direction is connected to a ball nut 23N (a predetermined operated position) at the other end 23a of the support arm 23. An example of a location) A weight 28 is provided to be located in the vicinity. The weight 28 is formed of a block made of a solid metal or the like, and is attached to a surface of the base end portion 23a as the input portion opposite to the exposure head main body 22 with respect to the ball nut 23N. The engagement portion of the linear guide member 23 is disposed between the exposure head main body 22 and the weight 28. A vacuum fluorescent tube (VF) type exposure head is used as the digital exposure head 21, and a first element array 21r in which first vacuum fluorescent tube elements for emitting a red light beam are arranged in the main scanning direction; A second vacuum fluorescent tube element for emitting a green light beam is arranged along the main scanning direction.
It comprises an element array 21g and a third element array 21b in which third vacuum fluorescent tube elements for emitting blue light beams are arranged in the main scanning direction. Each element array 21r, 21g, 2
1b is a photographic paper SP with a vacuum fluorescent tube element at about 200 dpi.
Has a length corresponding to the width of. Each of the first, second, and third vacuum fluorescent tube elements is an example of a light emitting element that can form a latent image of fine dots (an example of pixel information) on the printing paper SP by emitted light. . Digital exposure head 21
In addition to the vacuum fluorescent tube type exposure head, a light source such as an LED and the emission of light from the light source are turned on for each pixel.
A liquid crystal shutter type exposure head having a liquid crystal to be turned on / off, or an MLVA type exposure head using a shutter composed of a large number of optical fiber cables extending from a halogen lamp and an electro-optical element such as PLZT may be used. it can.

The photographic printer 100 is a film scanner (not shown) which optically reads an image of a photographic film F supported by a film carrier 14 and converts the image into digital image data as an input means of image information.
And a driver means (not shown) for extracting image information from a floppy (registered trademark) disk, MO, flash memory or other image information medium. Then, the control device creates print data based on the image information given via these input means, and based on the print data, moves the digital exposure head 21 by the ball screw mechanism 24 along the sub-scanning direction. By driving each of the element arrays 21r, 21g, 21b while transporting, a predetermined image can be line-exposed on the photographic paper SP, which is held stationary on the support surface of the exposure table 4.

Further, when the exposure operation is performed by the first exposure unit EUa, a part of the photographic paper SP held on the exposure table 4 is shielded from transmitted light by the frame member 20 so that the photographic paper SP is protected. In order to form white borders on the four sides, a mask means arranged to face the exposure table 4 is provided. The mask means includes a pair of first light shielding plates 3 extending along the sub-scanning direction of the digital exposure head 21.
0a, 30b and a pair of second
It comprises light shielding plates 31a and 31b. The first light shielding plate 30a,
Both 30b and the second light shielding plates 31a and 31b are supported on the frame member 20 so as to be movable in the gap between the lower surface of the digital exposure head 21 and the printing paper SP.

The first light shielding plates 30a and 30b are connected to a part of a timing belt (not shown) stretched between a pair of pulleys (not shown), and based on an instruction sent from the control device. It is configured to be movable by a drive motor (not shown) that rotationally drives the lever timing belt. The second light shielding plates 31a and 31b can also be moved and operated based on an instruction sent from the control device by the same configuration as the first light shielding plates 30a and 30b. Incidentally, one of the second light shielding plates 31a and 31b can be substituted by a light shielding plate fixed to the digital exposure head 21 itself. Further, when performing the exposure operation by the first exposure unit EUa on the photographic paper SP held on the exposure table 4, since the digital exposure head 21 does not intervene in the optical path of the transmitted light,
It is configured to be retracted to a home position provided at one end in the sub-scanning direction. However, the second light shielding plate 31
This does not apply to the case where one of a and 31b is provided in the digital exposure head 21. The second exposure unit EUb includes a drive current for the drive motor 26 of the digital exposure head 21, an electric signal for controlling the rotation amount of the drive motor 26, and a drive current for each vacuum fluorescent tube element of the digital exposure head 21. And an input connector (not shown) for receiving an electric signal for control and the like from the main cabinet BC of the photographic printer 100.

[Alternative Embodiment] A digital print head, such as a digital exposure head 21, in which a number of pixel forming elements capable of recording pixel information on recording paper are arranged in the main scanning direction, reciprocally move in the sub scanning direction. The driving means to operate is
The present invention is not limited to the ball screw mechanism 24 used in the above-described embodiment. For example, at the same time as the whole is stretched between a pair of pulleys, Alternatively, a mechanism using an endless timing belt fixed to the operated portion may be used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a photographic printer according to the present invention.

FIG. 2 is a schematic diagram showing main components of the photographic printer of FIG. 1;

FIG. 3 is a perspective view showing a second exposure unit of the photographic printer of FIG. 1;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photographic paper magazine 3 cutter 4 exposure table 5 endless belt 20 frame member 21 digital exposure head 22 exposure head main body 23 support member 23N ball nut (input nut, predetermined operated part) 24 ball screw mechanism 25 ball screw 26 drive motor 27 linear guide Member 28 Weight BC Cabinet De Developing Unit Dr Drying Unit EUa First Exposure Unit EUb Second Exposure Unit Ex Exposure Unit LP Photographic Paper (Roll, Recording Paper) SP Photographic Paper (Rectangle Sheet, Recording Paper)

Claims (4)

[Claims] 1. A digital print head in which a large number of pixel forming elements capable of recording pixel information on a recording sheet are arranged along a main scanning direction, and at a predetermined operated position of the digital print head in the main scanning direction. A driving unit for reciprocating the digital print head in a sub-scanning direction intersecting with the main scanning direction by applying an operating force, wherein the predetermined operated portion is An image forming apparatus arranged near a center of gravity of the digital print head in a main scanning direction. 2. The image forming apparatus according to claim 1, wherein a weight for displacing the center of gravity of the digital print head to the predetermined operated position is attached to the digital print head. 3. A digital print head in which a large number of pixel forming elements capable of recording pixel information on a recording paper are arranged along a main scanning direction, and at a predetermined operated position of the digital print head in the main scanning direction. A driving unit for reciprocating the digital print head in a sub-scanning direction intersecting the main scanning direction by applying an operating force, wherein the digital print head is A print head body including a pixel forming element, and while supporting the print head body on one side in the main scanning direction,
An input unit including the predetermined operated part, wherein a weight for positioning the center of gravity of the digital print head near the predetermined operated part in the main scanning direction is based on the predetermined operated part. And an image forming apparatus attached to the input unit at a position opposite to the print head body. 4. The driving means has a screw shaft extending along the sub-scanning direction, and a drive motor for driving the screw shaft to rotate, and the input unit is screwed with the screw shaft. Further comprising an input nut fixed to the digital print head, further provided with a guide mechanism for restricting rotation of the digital print head around the screw axis, wherein the guide mechanism is parallel to the screw axis. 4. A rod-shaped guide member extending to the guide member, and an engaging portion provided between the print head body and the weight so as to engage with the guide member while sliding with respect to the guide member. The image forming apparatus as described in the above.